Instant messages are short text messages with no subject and no attachments sent directly from terminal to terminal within an instant messaging (IM) community. The messages are generally displayed to the user as part of a conversation. A member of an instant messaging (IM) community has a unique identifier (“contact name”) in that community and can be added to the contact list of another member of the community using that identifier. For example, SMS is available only within the community of mobile telephone users, and the unique identifier is the telephone number.
A user receiving an IM message to his communication device may type and send a response to the message. However, it may take some time for the user to notice the received message, to read it and to type and send the response. If the user is not available to receive the message, the sender of the message may wait a long time for a response before realizing that the user has not participated in the conversation.
Some IM systems use notifications to provide users with “clues” about the status of a conversation. For example, a Message_Delivered notification may be used to notify a sender of a message that the message was received by the target communication device. In another example, a Message_Read notification may be used to notify a sender of a message that the message was read by a user of the target communication device. In yet another example, Typing_Started and Typing_Stopped messages may be used to notify a sender of a message when a user of the target communication device is typing a response to the message.
Notifications sent in an IM system occupy bandwidth that would otherwise be available for other communications.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity.